1. Field of the Invention
This invention relates to battery vent plugs and in particular to such vent plugs having flame arresting means.
2. Description of the Background Art
In one early form of battery vent plug illustrated in U.S. Pat. No. 1,459,121 of F. Van deWiel, the vent plug is defined by a body portion and an insert portion threaded to the body portion. The body and insert cooperatively define a tortuous passage for the flow of gases outwardly from the battery while causing liquid particles carried in suspension by the gases to be returned to the battery.
Another form of battery vent plug is illustrated in U.S. Pat. No. 3,108,911 to James H. Miller. As disclosed therein, the vent plug includes a mushroom insert portion depending from a closure across an upper end of an outer body portion. The body portion is further provided with a cylindrical inner surface formed with a plurality of vertically extending ridges functioning as baffles to intersect upwardly spiraling spray and return it to the battery cell.
Roy E. Henton shows, in U.S. Pat. No. 3,466,199, a battery vent plug having a microporous disc vent across the upper end of the vent outlet.
In a subsequent U.S. Pat. No. 3,879,227, of Roy E. Hennen, the patentee discloses the use of a ceramic porous diffuser in a mounting structure adapted for retention and drainback of the electrolyte liquid.
George E. Gross, in U.S. Pat. No. 3,915,752, shows a battery vent plug having a flame barrier filter provided with a domed configuration, permitting the edge thereof to be compressed so as to make the peripheral portion of the filter substantially nonporous to escaping battery gas so that any flame that results from ignition of the vented gas will tend to be confined in the center of the filter. The filter is made of a material having low heat conductivity.
Duane D. Hakarine discloses in U.S. Pat. No. 4,002,495, which patent is owned by the assignee hereof, an explosion-proof vent barrel for a battery having a porous flame-arresting disc carried in the vent barrel body. The device further includes an electrolyte splash baffle.
Jeffrey S. Leeson et al., in U.S. Pat. No. 4,072,799, show a vent plug system for batteries provided with baffles arranged inside the vent plug assembly such that the fluid entering the primary inlet thereof flows in a horizontal direction and is scrubbed to remove the electrolyte therefrom for return to the cell through a drain opening. The vent plug has a low profile so as to be used also on maintenance-free batteries.